#define _CRT_SECURE_NO_WARNINGS 1
#include<stdio.h>
int main()
{
	int m = 0;
	double sum = 0;
	int arr[10] = { 0 };
	for (m = 0; m <= 9; m++)
	{
		scanf("%d", &arr[m]);
		sum += arr[m];
	}
	printf("%lf", sum/10);
}